Lee planned to have his "Old War Horse" General James Longstreet lead an echelon attack rippling along the Union's left flank while Early's and Johnson's divisions of the II Corps were to "demonstrate" against the right flank at Culps Hill going to a full on attack if success seemed likely.
Unfortunately for Lee the Union right flank was virtually impregnable and the Rebel forces suffered "considerable casualties."
Worse luck awaited on the left. Instead of an undefended flank, Longstreet ran into the the Union III Corps commanded by General Daniel Sickles who had advanced his unit to higher ground than he had been assigned, including this spot on Little Round Top where Longstreet's advance was spotted.
Sickles' line was stretched too thin, broken in one place with an untenable salient at the Sherfy farm's Peach Orchard (which the NPS has re-planted).
Longstreet's attack broke that line, but Meade threw an additional 20,000 reserves into the field. Sickles' III Corps was "virtually destroyed as a combat unit" and Confederate forces -- briefly -- reached Cemetery Ridge.
But essentially thanks to the foresight of General Gouvernor Warren seen here from behind, Little Round Top dominated the so-called Valley of Death below it.